Finishing Versus Orbital Sander (from Amateur Woodworker)

Approximate Cost

Finishing Sanders: from S$44
Random Orbit Sanders: from S$119.90

Description

Finishing sanders come in two main types: block sanders and random orbit. Although either tools can be used as a finishing sander, they excel at different applications. Random orbit sanders are better for sanding large areas quickly. However, finishing/block sanders provide a better finish while also have the obvious advantage of being able to get closer into the corner as they do not have a circular base like orbital sanders.
Further, block sanders can use standard sandpaper that you cut down to shape, while random orbit sanders need specific circular sheets and this can make the running cost higher. If you only have the money for one of these sanders, we recommend a block/finishing sander. While it will take longer to get a good finish, the end result will be far better.
When purchasing a sander consider the following:

• How rapidly does the sander vibrate. This measurement is often in orbits per minute (OPM). The faster it vibrates, the quicker it will sand.
  
• Some sanders offer a variable speed option and this is worth considering as long as the price differential is low.
  
• Do not be overly concerned about the dust collection system. Many of these do not work very well anyway.
  
• If you do want a dust collection system, ensure that your sander comes with a hole punch system so that you can easily punch dust holes in standard sandpaper, rather than having to buy special paper (this only applies to block sanders -- orbital sanders require special paper anyway).
  

Using the sander

The normal weight of the sander is sufficient to sand and there is no need to exert extra pressure. Contrary to popular belief, additional pressure is detrimental to efficient sanding as it slows the speed of the pad.
Finishing sanders cause thousands of small abrasive grits to move in circular obits against the wood at a high speed. Each grain moves in the same direction, ensuring that the cutting action is uniform over the whole area. You should try to cover each part of the wood from many different directions to ensure that you get an even finish that does not have a bias towards movement in one particular direction.
Begin the sanding process with a relatively coarse paper (the coarseness will depend on how much sanding there is to do) and then move down to finer paper. Do not go from a coarse paper straight to a fine one, but step through the various grades. Too great a step will mean that you cannot sand out the "swirls" caused by the coarser paper.
Successful sanding is a result of patience and perseverance. The more time you spend on this step, the happier you will be with the final result.